配置springmvc在其他类中（spring容器外）获取注入bean

学习https://github.com/thinkgem/jeesite

今天在写JedisUtils的时候要注入JedisPool，而这个属性被设置为static，@Resource和@Autowired都不可以注入，因为spring不能为静态变量依赖注入。因此需要额外的方法获取spring管理的bean。本文即SpringContextHolder：

 package com.demo.common.utils;

 import org.apache.commons.lang3.Validate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Service;

 /**
  * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
  * Created by Administrator on 2016/2/23.
  */
 @Service
 @Lazy(false)
 public class SpringContextHolder implements ApplicationContextAware ,DisposableBean {
     private static ApplicationContext applicationContext = null;
     private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

     /**
      * 去的存储在静态变量中的ApplicationContext
      * @return
      */
     public static ApplicationContext getApplicationContext(){
         assertContextInjected();
         return applicationContext;
     }

     /**
      * 从静态变量applicationContext中去的Bean，自动转型为所复制对象的类型
      * @param name
      * @param <T>
      * @return
      */
     public static <T> T getBean(String name){
         assertContextInjected();
         return (T)applicationContext.getBean(name);
     }

     /**
      * 从静态变量applicationContext中去的Bean，自动转型为所复制对象的类型
      * @param requiredType
      * @param <T>
      * @return
      */
     public static <T> T getBean(Class<T> requiredType){
         assertContextInjected();
         return (T)applicationContext.getBean(requiredType);
     }

     /**
      * 清楚SpringContextHolder中的ApplicationContext为Null
      */
     public static void clearHolder(){
         if(logger.isDebugEnabled()){
             logger.debug("清楚SpringContextHolder中的ApplicationContext:"+applicationContext);
         }
         applicationContext = null;
     }

     /**
      * 检查ApplicationContext不为空
      */
     private static void assertContextInjected() {
         Validate.validState(applicationContext!=null,"applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
     }

     /**
      * 实现ApplicationContextAware接口，注入Context到静态变量
      * @param applicationContext
      * @throws BeansException
      */
     @Override
     public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
         SpringContextHolder.applicationContext = applicationContext;
     }

     /**
      * 实现DisposableBean接口，在Context关闭时清理静态变量
      * @throws Exception
      */
     @Override
     public void destroy() throws Exception {
         SpringContextHolder.clearHolder();
     }
 }